392.46 Bushed Conduit and Tubing.

Cables entering equipment from bushed conduit and flanged connections.
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Cables entering equipment from bushed conduit and flanged connections.

Code Change Summary: New code language providing specifics on cables and conductors transitioning from a cable tray into the equipment.

In the past, the language permitting cables to transition from a cable tray into the associated equipment has been vague at best. The two most common methods to transition from a cable tray to the equipment are:

  1. Cables or conductors leaving the cable tray and entering the equipment through a raceway with a bushing on the end (see image A).
  2. Cables or conductors leaving the cable tray and entering the equipment through a flanged opening on top of the equipment (see image B).

In the 2020 NEC®, the above methods have been introduced with new subsections A and B in 392.46. Additionally, both methods now require the raceway or flange opening to be sealed or covered to prevent debris from entering the enclosure through the opening.

The new informational note mentions sealing the raceway or the flanged opening with duct seal as an option.

Below is a preview of the NEC®. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2020 NEC® edition of NFPA 70.

2017 Code Language:

392.46 Bushed Conduit and Tubing. A box shall not be required where cables or conductors are installed in bushed conduit and tubing used for support or for protection against physical damage.

2020 Code Language:

392.46 Bushed Conduit and Tubing. A box shall not be required where cables or conductors are installed in bushed conduit and tubing used for support or for protection against physical damage or where conductors or cables transition to a raceway wiring method from the cable tray. Conductors shall be permitted to enter equipment in accordance with 392.46(A) or (B).

N (A) Through Bushed Conduit or Tubing. Individual conductors or multiconductor cables with entirely nonmetallic sheaths shall be permitted to enter enclosures where they are terminated through nonflexible bushed conduit or tubing installed for their protection provided they are secured at the point of transition from the cable tray and the conduit or tubing is sealed at the outer end using an approved means so as to prevent debris from entering the equipment through the conduit or tubing.

N (B) Flanged Connections. Individual conductors or multiconductor cables with entirely nonmetallic sheaths shall be permitted to enter enclosures through openings associated with flanges from cable trays where the cable tray is attached to the flange and the flange is mounted directly to the equipment. The openings shall be made such that the conductors are protected from abrasion and the opening shall be sealed or covered to prevent debris from entering the enclosure through the opening.

Informational Note: One method of preventing debris from entering the enclosure is to seal the outer end of the raceway or the opening with duct seal.

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392.46 Bushed Conduit and Tubing.

Below is a Real Question from our Electrical Continuing Education Courses for Electrical License Renewal:

Based on the 2020 NEC, which of the following is true?

A: The raceway or flanged opening shall be sealed or covered to prevent debris from entering the enclosure through the opening.
B: Cables are NOT permitted to transition from a cable tray to the equipment through a bushed conduit.
C: Cables are NOT permitted to transition from a cable tray to the equipment through a flanged connection.
D: A box is required where cables or conductors exit a cable tray and are installed in bushed conduit and tubing used for support.
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